This invention represents an improved device for simultaneous measurement of the flow velocity and density of a fluid flowing in a tubular member. In particular this invention has been developed to meter nonhomogeneous mixtures of water and steam in high-pressure water lines of a nuclear reactor. Until recently the measurement of fluid velocity and density had been accomplished by a device containing a turbine for velocity determination and a separate drag disc for measurement of momentum flux (density may be determined from the velocity and the momentum flux). The use of separate units to measure velocity and momentum flux may, however, result in anomalous data collection due to the shadowing effect one measuring unit has on the other. Further, each unit necessarily measures a different volume element of the flowing fluid, which can be quite inhomogeneous for two phase mixtures such as water-steam.
The limitations imposed by separate measuring units have been overcome in another invention by the applicant J. H. Cole, "Device for Measuring the Fluid Density of a Two Phase Mixture", Ser. No. 957,618, filed Oct. 30, 1978, now U.S. Pat. No. 4,196,613. The novel achievement was the use of a single rotor blade assembly to determine both the fluid velocity and drag force simultaneously for the identical sample of fluid. This unit functions as intended unless the fluid contains a dispersion of small particulate matter, which can be a contaminant or corrosion product in high-pressure water lines. Accumulation of such particulate on the bearing surfaces eventually leads to bearing seizure and failure of the fluid metering device.
It is therefore an object of the present invention to provide a device capable of measuring the density and velocity of a fluid flowing through a tubular member.
It is also an object of the this invention to provide a device which can measure concurrently the velocity and density of the identical fluid sample flowing through a tubular member.
It is a further object of the present invention to provide a device which can measure the density and velocity of flowing fluid containing a dispersion of small particulate matter without such matter causing bearing failure.